The present invention relates to improvements in mechanisms for preparing stock for papermaking machines, and more particularly to an inlet flow distributor for a stock filter.
One of the operations in the preparation of stock for a papermaking machine is filtering the stock, whether such stock is original virgin stock or whether it is reprocessed stock, the fibers are suspended in a liquor or a liquid suspension and fed to a filter which separates the fibers from the liquor. The filters generally have a broad or an elongate filter area and a frequently used filter construction employs a plurality of rotatable disks mounted on a horizontal axis with the stock preferably fed to an elongate receiving chamber. For optimum effectiveness of the filtering operation, it is desirable that all of the filter disks along the chamber be supplied with stock at uniform velocity so that each of the filter disks carries or receives an equal flow. Devices for supplying stock to the filter arrangement have frequently employed cascading pipes which do not insure uniform flow across the length of the filter, which are expensive to build and consume unnecessary space.
It is accordingly an object of the present invention to provide an inlet flow distributor such as for a multiple disk filter which avoids the disadvantages of structures heretofore available such as cascading pipe arrangements and which is capable of continual operation in feeding and distributing a flow of stock uniformly across the filter.
A further object of the invention is to provide a flow distributor and filter wherein the flow is conducted through a transverse tapered header and is distributed along the filter vat by a series of L-shaped vanes having a lead-in arrangement which reverse the direction of flow as it enters the distributor.
A further object of the invention is to provide a flow distributor and filter arrangement wherein the flow to the filter is uniform, and the system is not large or cumbersome nor expensive to fabricate and does not require relatively large space for installation.
A feature of the invention is the provision of a feed system with a filter consisting of a single channel extending along the entire length of the filter chamber or vat having an array of baffles of unique design which turn the flow in a direction opposite to the entry flow and direct it into the vat. The entry channel is supplied by a single inlet pipe eliminating the branching array of inlet pipes of structures heretofore available. The bottom of the channel is tapered upward in the direction of flow to maintain an essentially constant velocity in the channel. The baffles arranged along the channel are L-shaped having a main wall portion with a short entry leg portion which projects in the direction of flow in the channel so that the flow must flow around the entry portion to reverse its direction. The baffles are thus L-shaped with the foot of the L smoothly rounded with enough radius to prevent the fibers from stapling to it, and the main wall portion long enough to effectively turn the direction of flow and prevent a significant cross direction component of velocity. The short or entry leg restricts the area available for flow to leave the channel and enter the spaces between the baffles providing some resistance to flow which contributes to the evenness of distribution.
Other objects, advantages and features, as well as equivalent structures which are intended to be covered herein will become more apparent from the teaching of the principles of the invention in connection with the disclosure of the preferred embodiment thereof in the specification, claims and drawings, in which: